Aldose reductase (AR), an enzyme which converts sugars to sugar alcohols, has been implicated in diabetic complications of the eye and the peripheral nerves. Our studies have focused on isolating and characterizing the gene for aldose reductase. As an initial step, putative AR cDNA clones from a bovine retina cDNA Lambdagt 11 library were isolated and sequenced. Sequencing of three non-homologous inserts yielded approximately 700 nucleotides or around one-third of the full length mRNA. Northern analysis showed that the full size of AR mRNA is around 2 kilobases in the bovine retina and slightly larger in the bovine brain. Homologies between the bovine retina AR cDNA and mRNAs from cultured dog lens epithelial cells and cultured rabbit kidney cells have not been detected. Retriction enzyme analysis of total bovine genomic DNA indicates that fewer than 3 genes are present.